Fibrous glass insulation (“fiberglass” or “glass fiber” insulation) products generally comprise matted glass fibers bonded together by a binder that is often a cured thermoset polymeric material. Molten streams of glass are drawn into fibers of random lengths and blown into a forming chamber where they are randomly deposited as a mat onto a traveling conveyor. The fibers, while in transit in the forming chamber, and while often still hot from the drawing operation are sprayed with the binder. The coated fibrous mat is transferred to a curing oven where heated air, for example, is blown through the mat to cure the binder and rigidly bond the glass fibers together.
Fiberglass binders have a variety of uses ranging from stiffening applications where the binder is applied to woven or non-woven fiberglass sheet goods and cured, producing a stiffer product; thermo-forming applications wherein the binder resin is applied to sheet or lofty fibrous product following which it is dried and optionally B-staged to form an intermediate but yet curable product; and to fully cured systems such as building insulation.
Binders useful in fiberglass insulation products generally require a low viscosity in the uncured state, yet characteristics so as to form a rigid thermoset polymeric mat for the glass fibers when cured. A binder which forms a rigid matrix when cured is required so that a finished fiberglass thermal insulation product, when compressed for packaging and shipping, will recover to its specified vertical dimension when installed in a building.
From among the many thermosetting polymers, numerous candidates for suitable thermosetting fiber-glass binder resins exist. However, binder-coated fiberglass products are often of the commodity type, and thus cost becomes a driving factor, generally ruling out such resins as thermosetting polyurethanes, epoxies, and others. Due to their excellent cost/performance ratio, the resins of choice in the past have been phenol/formaldehyde resins. Phenol/formaldehyde resins can be economically produced, and can be extended with urea prior to use as a binder in many applications. Such urea-extended phenol/formaldehyde binders have been the mainstay of the fiberglass insulation industry for years.
Over the past several decades, however, minimization of volatile organic compound emissions (VOCs) both on the part of the industry desiring to provide a cleaner environment, as well as by Federal regulation, has led to extensive investigations into not only reducing emissions from the current formaldehyde-based binders, but also reducing the amount of binder used in production. Increasing stringent Federal regulations has lead to greater attention to alternative binder systems which are free from formaldehyde.
One particularly useful binder system which is substantially free of formaldehyde employs a binder comprising a polycarboxy polymer and a polyol. Resins free of formaldehyde are those which are not made with formaldehyde or formaldehyde-generating compounds. Resins, such as acrylic resins, do not emit appreciable levels of formaldehyde during the insulation manufacturing process and do not emit formaldehyde under normal service conditions. Use of this binder system in conjunction with a catalyst, such as an alkaline metal salt of a phosphorous-containing organic acid, results in glass fiber products that exhibit excellent recovery and rigidity properties.
Fiberglass products, such as fiberglass insulation, are exposed to a variety of environmental conditions that can adversely affect the performance of the product. Overall rigidity and recovery of the product are typical measures of performance.
Curing of the fiberglass products is essential to proper product performance. Factors that contribute to the curing process, and the ultimate performance of the fiberglass product, include many variables, and ultimate product performance is often unpredictable.
There is a need for reducing the quantity of acrylic resin used in binder systems during the manufacture of fiber glass insulation products without negatively impacting the curing process or the overall performance of the product. Even more so, there is a need for reducing the amount of acrylic resin used while improving the overall processing and performance of the product.
The foregoing examples of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.